[sdiy] A Synth DIY weekend...

[patchell]

    Well, this was the first weekend since I got back from the PNW on
DEC 30 that I could actually get back to work on projects (both myself
and Homer (cat) were sick after I returned, I had a cold, and Homer had
a urinary blockage..ouch!).

    I worked a bit on the logic module.  I split it up.  It is now going
to be two PC boards (I haven't posted schematics yet).  I got the 4x4
And-Or logic board layed out.  One problem I ran into with the Mikado
was in the use of diode clamps on HC logic.  While the diode clamps
worked just great, the fact that logic 1 happens at about 3.5 Volts or
so made the logic kind of in compatible with some synthesizers that only
swung +/- 2.5 volts.  I am going to try and used 14C89 rs232 receivers
to fix this problem.  They still run on 5 volts, you can adjust the
threshold, and they will tolerate the +/-12 volt swings that they could
get...

    Also, I worked a bit on the Rogers Glockenspiel I am converting over
to Midi.  I took it all apart today to fix the two notes that wouldn't
play.  Turns out the little plungers were stuck in decaying foam that
Rogers used to damp out the thump the plungers would have made if they
hit the wood...although, that was another reason I took it apart, to
replace that foam with felt...the felt works, although there is still a
bit of a thump, but nothing like it was.  Also, the phenolic board that
has the solenoids on it was stapled to the wood frame.  It was really
fun getting those staples out.  The phenolic was just a bit brittle, but
no major problems.

--
 -Jim
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* Visit:http://www.silcom.com/~patchell/
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*I'm sure glad Merry Christmas comes just once a year
* -Yogi Yorgensen
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